We just beamed a signal at space aliens. Was that a bad idea?

In a valley eight miles southeast of the Norwegian city of Tromsø, a radar antenna has just transmitted a short bit of radio programming to potential alien listeners: some specially composed electronic music and a tutorial about geometry and the use of binary numbers.

This isn’t the usual approach to the search for extraterrestrial intelligence (SETI). Ordinarily, scientists engaged in SETI use such antennas with the hope of hearing a signal that would have been broadcast tens, hundreds, or even thousands of years ago.